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Original Filed Aug. 26, 1926 schematic Patented Aug. 26,1930

1 UNITED STATES PATENT orrlcs JOHN WICKS, OF OAK PARK, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO AUTO- MATIC ELECTRIC INC OF CHICAGO, ILLINOIS, A CORPORATION OF DELAWARE AUTOMATIC TELEPHONE SYSTEM Original application filed August 26, 1926, Serial No. 1929. Serial This invention relates to telephone systems in general, but is more particularly concerned with automatic telephone systems in which toll connections are established through the medium of operator-controlled automatic switches. In such a system, automaticswitches such as a toll first selector, toll transmission selector, one or more intermediate selectors, and a connector are successively operated under the control of a dial at thetoll operators positions. This invention further pertains especially to that kind of automatic telephone system in which the motor magnets of the automatic switches are directly operated by current impulses produced by the line relay of the transmission selector, the line relay of the transmission selector being operated by impulses produced by the dial of the calling operator.

The main object of this invention is the provision of new and improved automatic switches for use in a direct pulsing automatic telephone system. Themain feature resides in the circuit arrangement whereby the our rent impulses foroperating the magnets of the switches produced by the line relay of the first selector repeater are transmitted to the magnets of the switches over the two sides of the extended trunk line in series.

Other objects are accomplished and various features are contained in the invention which will be fully described in the body of this specification with the aid of the accompanying drawings.

This application is a division of my prior application Serial No. 131,575, filed August 26, 1926. Those features of the invention which relate generally to toll service are claimed herein, while the features relating to local service are claimed in the prior application.

Referring now to the accompanying drawings, Figs, 1-3 show by means of the usual circuit diagrams a sufiicicnt amount of the apparatus in a telephone system embodyingthe principles of this inven tion to enable the invention to be clearly described and understood.

The rightehand half of Fig. 1 shows'the 50 incoming toll selector TS. This toll selec- 131,575. Divided and this application filed July 15, No. 378,225.

tor terminates one of the toll trunks incommg from the office in which the main toll board is located. As many incoming toll,

The left-hand half of Fig. 1 shows the toll operators cord CC by means of which toll connections are established over trunks extending to the various offices in the system, each trunk terminating at the toll board and a jack such as jack J. This cord is of standard type and forms no particular part of the invention itself. The circuit thereof will be described only inso far as is necessary to fully describe other apparatus controlled by means within the cord.

Fig. 2 shows the toll transmission selector T'TS, which is one of a certain group of toll transmission selectors accessible in the banks of the incomingtoll selectors. The banks of the toll transmission selectors are directly multipled with the'banks of the local third selectors, and the toll transmission selectors and localthird selectors are thereby given common access to the connectors.

Mechanically. the toll transmission selector TTS is also of the Strowgervertical and rotary type. The circuit arrangements, howver, have been modified to meet the requirements of the invention and will likewise be described in detail hereinafter. I

Fig. 3 shows the rotary connector RC, which is like the local connectorC, shown in the above-referred-to application, except that it performs an automatic rotary hunting movement after com 'ileting its rotary directive movement. In its banks, access is bad to groups of lines extending to private'branch exchanges with the number of the first line assigned as the call number of the entire group. The rotary connector RC is one of a group of rotary connectors accessible in the banks of a certain group of local third selectors inultipled with the banks of a certain 'roup of toll transmission selectors. The nrst and last trunk of a group extending to the private branch exchange X, accessible to connector RC, are shown. Each trunk terminates in an individual line switch such LS at the main exchange, and in a jack such as jack J at the branch exchange. The line switch LS is of the well known rotary ty having no normal or home position. A scription of the operation of connector EC in so far the novel features relating to this invention are concerned will also be given.

To establish toll connections iron]. the main toll board to a local P. A. X. subscriber, a new type of toll transmission selector, designed especially to meet the requirements or" this invention, has been provided. To describe the operation of this new type of toll transmission selector and to describe the operation oi the new connector herein provided when utilized in a toll connection, it will be assumed that a toll connection is desired with a sub scriber at the P. A. v (Fig. In

1\. 1; this telephone system it is assumed that the main toll board is located at one exchan 'e, from which toll trunks ex end. to the other exchanges in the system.

It may now be assumed that the toll operator at the main toll board position answers the incoming toll call by means oi. the cord circuit CC, Fig. l, and, having learned the name or number of the called subscriber or P. A. X. inserts the calling plug P of the cord CC into the jack of an idle toll trunk extending to the exchange serving the called subscriber. It may further be assumed, that the trunk selected is the one. con'iprising conductors 501 and 502, tern'iinating at the. exchange under consideration in the selector As previously stated, the selector TS is of the well-known Strowger "vertical and rotary type. the operation of which is well understood by those skilled in the art, and there- 'lore a detailed. description of its operation is thought unnecessary. fitter the toll operator inserts the plug P into the jack J she dials the directory number oi the called subscriber. Responsive to the dialing 01" the first digit of the called number, the selector S operates to position its wipers opposite the level ot banlr contacts, correspondin to the digit dialed, and then antomaticall rotates to position its wipers F51558 on a set ot bank contacts ter minating an idle trunk.

It may be assumed that the idle trunk selected the one comprising conductors accessible at banl: contacts %556. It may be mentioned that the first digit of the called number concerns the toll operator is the second digit in the directory number of the desired station, since the operator in completing the I orl-zing contact and armature trunk conductor 502, ring of jack J, ring oi pl g P, contacts 5G3, contacts 505, lower 1! gb -liand winding of repeating coil R, winding 0% polarized relay 502, upper rightl'iand winding oi repeating coil l contacts 506, contacts 504, tip of plug 1?, and tip of jack J, conductor 501, armature 521 and the working contact, wiper 551, bani; contact 554, conductor 55a, normally closed springs controlled armature (323, normally closed springs controlled by armature (528, through the upper winding of line relay 605 to battery. Line relay (305 operates and opens the short circuit around re sistance 619 and the upper winding of holding relay 608 at armature 632, and closes a circuit for release relay 606 at armature Gill. Relay 606 operates and performs the following circuit. changes: Ground potential is placed on release conductor 555 to make the trunk engaged and to provide a holding circuit for selectors TS at armature 633, this taking place before the release relay in the selector TS has had time to fall back. A point in the circuit of release magnet (31 i is opened at armature (53 1-. The circuit of the series relay 609 is prepared at armature 0235, relay 609 being maintained deenergized at this time by reason of ground potential. on its upper terminal by way of the working contact and arn'iature (331. At armature Gill; a circuitis closed which may be traced from ground on the. release conductor supplied thereto by way of armature 33 and the \VOIlI- ing contact, normally closed. springs con trolled by arn'iat-nre hi8, arn'uiturc (ll-(i and the resting contact. aru'iature ($36 and the working contact, resistance (51), through the upper winding of relay (Hi3, arn'iatnre (i241 and the resting contact. syn'ings controlled by armature 652, through the winding of vertical magnet 612 to battery Due to the resistance of the upper winding OIii re ay (30S and resistance 619, the current lion of this circuit insufficient to cause the operac' on of magnet 612. Relay 6 8 operates, however, and performs the following circuit changes: At armature G il and the working contact, a circuit is closed for the supervisory relay 690 and lamp L in series, at the same time preparing the circuit for the lower winding of relay 608. At armatures 64-2 2nd 640 a new circuit is closed for the upper winding of relay (508 which may be traced from ground by way of the normally closed springs controlled by armature 647, armature 640 and the working contact, armature 636 and the working contact, resistance 619, upper Winding of relay 608, working contact and armature 642, normally closed springs controlled by armature 652, through the Winding of vertical magnet 612 to battery.

Responsiveto the next digit dialed by the toll operator, line relay 605 deenergizes and reenergizes a corresponding number of times.

As a result, resistance 619 and the upper winding of relay 608 are short circuited, at armature 632 and the resting contact, a like number of times which causes corresponding impulses of increased current flow in the circuit of the vertical magnet 612. Responsive thereto, vertical magnet 612 operates to position the Wipers 661 664 opposite the level of bank contacts corresponding to the digit dialed. Furthermore, each timethat relay 605 deenergizes, ground potential is disconnected from the upper terminaloi the series relay 609 and. batterythrough the resistance 615 is substituted therefor by way of armature 631 and the resting contact. Relay 609, therefore, energizes over the circuit from ground through its own winding, working contact and armature 635 to battery byway of armature 631 and the resting contact and resistance 615, and also to battery through the winding of'relay 606. Each time that relay 605 reenergizes during impulses, relay 609 is short circuited, and by reason of its being short circ-uited, assumes slow-acting char acteristics and, therefore, does not deenergize during the transmission of a series of impulses. Relay 609, in operating, closes an initialenergizing circuit for stepping relay 610 at armature 644 which circuit maybe traced from ground onrelease conductor 555, working contact and armature 644, resting contact and armature 650, oif-normal springs 654 which are closed upon the first vertical step of the switch wipers, through the winding of stepping relay 610 to battery. Relay 610 operates andprepares a circuit for the rotary magnet 613 at armature 645. In operating, relay 609 also closes the circuit for the lower locking windingof relay 608 at armature 643. The closure of this holding circuit positively assures the continuousoperation of relay 608 during the-transmission of impulses, that is, during the time its upper winding is short circuited. 'Relay 610 also closes a temporary locking circuit for itself at armature 646 which'may be traced from ground on release conductor 555, normally closed springs controlled by\ armature 648, armature 646 and the working contact, interrupting springs 653, oft-normal springs 654, through the winding of relay 610 to battery.

At the end of this-series of impulses, line relay 605 is no longer deenergized andiremains energized continuously. Relay 609 is again continuously short circuit-ed at armature 631 and the working contact and deenergizes. In releasing its armature 644, permitting the contacts controlled thereby to close, acircuit is closed for the rotary magnet 613 which may be traced from ground on release conductor 555, springs controlled by armature 644, working contact and armature 645, through thewinding of rotary mag net 613 to battery. Armature 643 in releasing again closes the circuit for the supervisory relay 690. Rotary magnet 613 operates over the above-traced circuit and rotates the switch wipers 661-664 into engagement with the first set of bank contacts in the selectedlevel and also opens the holding circuit for the stepping relay 610 at the interrupting contacts 653. Stepping relay 610 deenergizes and opens its own locking circuit at armature 646, and opens the circuit of the rotary magnet 613 at armature 645. Magnet 613 releases and again closes interrupt-ing springs 653. If the trunk line terminating in this first set of bank contacts is busy, ground potential will be present on the test contact encountered by test wiper 662. A circuit is then again closed for stepping relay 610 traceable from ground on the test contact, test wiper 662, armature 648 and the resting contact, interrupting springs 653, oilinornial springs 654, through the Winding of relay 610 to battery. Relay 610 again operates, closing the circuit of the rotary magnet 613 which again operates and steps the switch wipers into engagement with another set of bank contacts. In this manner stepping relay 610 and magnet 613 operate alternatively, until the switch wipers are rotated. into engagement with a set of bank contacts terminating an idle trunk. W hen an idle trunk line is found, which may be the trunk line comprising conductors 854-857 terminating in bank contacts 854857 no ground potential will be present on the bank contact 855. Consequently, no circuit will again be closed through the stepping relay 610. Therefore, the wipers will be arrested in engagement with this set of bank contacts. Fur hermore, the ground potential will be removed from the lower terminal of the switching relay 611, thus permitting this relay to energize over a circuit traceable from ground on release conductor through the winding of relay 611, interrupting contacts 653, ofi-normalsprings 654, through the winding of the stepping relay 610'to battery. Due to the high resistance of the switching relay 611 the current flow in this circuit is insuficient to cause the operation of stepping relay 610. Switching relay 611 operates, however, and performs the following circuit changes: Ground potential is supplied to the test contact 855 and releases conductor 855 by way o'f'wiper 662 and armature 648 and the working contact which is connected to the release conductor The trunk line is thus marl ied engaged and an obvious circuit closed for 1 re upper winding ol switching relay 801 of connector RC wiich terminates the selected trunk line. Switching relay 801 of connector RC operates in its first step to prepare the connector BC to receive the first of impulses. In operating, relay (5i 1 also prepares the circuit of reversing relay (302 at armature (S lt). At armature (350 a point in the initial circuit of stepping relay 010 is opened to prevent this relay from operat v r to the dialing of the next di 652 the connection is extended to the Elnector C, ground and battery through. magnet (3,1,2 being(l sroiiziectcil from the heavy talking conductors, and ground and.

through rotary magnet 809 and relay in series of connector RC being suliistitutcd therefor. Relay (308 remains energized over this circuit but relay 80% and magnet 809 do not operate due to the resistance in the circuit. At arn'iature ($51 :2 circuit is closed which may be traced from round by way ol armature 620 and the resting an act, armature 051 and the w r g contact, wiper 603, hank contacts 857 uclor ring ccntrol com 857, arn'iature 813 and the resting contact, through the upper winding o'l: ring-cu it relay 802, resistance 850 to hatti'u'y. Kiel-1 802 operates, closes a lo 1 circuit tor itself at armature 818, closes a point in the busy signalling circuit at armature 819, and at armatures 816 and 817 interrupts the ringing circuit, at the same time closing points in the talking circuit. A circuit is al o closed from ground on the release con 3 oil-normal springs 840 opened upon the first vertical. step oi the 'ii'ch \xipers, through the lower winding oi switching r 1y 80? to battery. Relay 80]", which nor. ions as a \'lll!li -')".(l' relay, operates and prepares a locking circuit for ell? at armature 83st, and at armature 833 li.-connc 1 the rotary magnet 809 and councils the vertical unr pe/t 808 in series with the series relay 80-l to the lo wer talking conductor by way oi arinature 8l5 and the esting contact. The actuation oi the other arniailures oi rel ay 80? has no ell cct at this time.

Responsive to the dialing of the next digit, resistance ($19 and the upper winding of relay 608 are short circuitcd by the deenergization of relay (305 as previously described and Vertical magnet 808 operates to raise the switch wipe 8l18 l'-l opposite the level of bank contacts corresponding to the digit (ll2lltd. Relay 804: energizes in series with magnet 808 and due to its slow-acting characteristic is maintained operated continuously during the transmission of the impulses. The actuation of armature 822 closes the circuit of slow-act ing relay 805. Relay 805 operates and maintains the locking circuit of. relay 807 at armature 828, this circuit including armature 83%. The circuit over which this relay is initially energized is opened at Vertical oil-normal springs 840 upon the first vertical step of the switch Wipers. At the end of this series of impulses relays 804 and 805 release as the short circuit is no longer placed around resistance 619 and the upper winding of relay 608, and tne locking circuit of relay 807 is interrupted. Relay 807 deenergizes and, by releasing armature 833. reconnects the rotary magnet 809 in serles with relay 80 i.

Responsive to the last series of impulses, rotary magnet 809 operates to rotate the switch wipers 84;l-8l. l into engagement with the set of bank contacts terminating the first trunl; ol the group of trunks extending to the private branch exchange X. During the transmission of this series of impulses relay 80% and 805 again operate, relay 805 at armature 824; and the working contact connecting test relay 806 to wiper 842.

The operation of the connector RC following the positioning of the switch Wipers 841- Sli upon the bank contacts terminating the first trunk of the group extending to the private branch exchange X depends on Whether this trunk is busy or idle at this time. It will be assumed that the first trunk of the group the one terminating in bank contacts 845 848, and that the last trunk of the group is the one terminating in bank contacts 845' 8l8. It the first trunk is busy at this time, ground potential will be present on bank contact 8&6, and bank contact 848 connected to bank contact 846 by way of the jumper 849. It may be mentioned that the test contacts similar to contacts 846 and 848 for all the other trunks of the group except the last trunk are connected together by means of jumpers such as jumper 849. As soon as wiper 8el-2 engages test contact: 840 a circuit is closed from ground potential on contact 846, wiper 84:2, armature 824 and the working contact, resting contact and armature 832, through the winding of test relay 806 to battery. Relay 806 operates and opens a point in the ring-back tone circuit at armature 827. prepares a circuit for the stepping relay 80?) at armature 829, and prepares the busy-tone circuit at armature 827. At the termination of this last train of impulses, relay 804 deengizes and by releasing armature 822 prepares a. holding circuit for the auxiliary series relay 805 and closes a circuit for the stepping relay 808 at armature 823 which circuit may be traced from ground on test contact 8L8, wiper 84 i, armature 829 and the Working contact, armature 823 and the resting contact, interrupting springs 836, through the winding of the stepping relay 803 to battery. Re lay 808 operates and closes a locking circuit for itself at armature 821 which extends from ground on the release conductor 855, rotary oil-normal springs 839 closed upon the first rotary step of the switch wipers, working contactjand armature 821, interrupting contacts 836, through the, winding of relay 803 to battery. At armature 820 the energizing circuit for the rotary magnet 809 and the holding circuit for relay 805 are closed. Thesecircuits may be traced from ground and release conductor 855, rotary off-normal springs 839, armature 820 and the working contact, then ,9 by way of resting contact and armature 822,

through the winding of relay 805 to battery,

and also by way" of the normally closed springs controlled by armature 833 through the winding ofrotary magnet 809 to battery. Consequently, relay 804 remains energized and magnet 809 operates rotating the switch wipers into engagement with the next set of bank contacts and also opening the circuit of stepping relay 803 at interrupting springs 836. Relay803 'deenergizes, opening its own holding circuit at armature 821, and opening the gcircuitfor relay 805 and magnet 809 at armature 820. Magnet 809 releases and again closes interrupting springs 836.

It the trunk line accessible in this next set o f ban .k cont acts is also busy, ground poten-' tial Wlll again be present on both bank cone tacts corresponding to contacts846 and 848. Again relay 803 will energize and close a cir-' cuit' for magnet 809, which results in the 'movement of the swltch wipers into engage ment with another set of bank contacts. In this manner the switch wipers will be rotated step by step until an idle trunk is. founder until the wipers are moved into engagement with the bankcontacts 845848 terminatingthe last trunk of the group of trunks eX- tending to the-desired private branch ex: change. V v

Assuming that wipers 841844 are rotated into'oen agement with thebank contacts ter- .minati'ng' the last trunk of the group, all the other trunks liavingtested busy, regardless.

' cit whether this last trunk is busy or idle, no

circuit will be again closed for stepping relay 803, since bank contact 848 is'not connected with bank contact 846. Consequently, the wipers will be arrested in this position.

It may be assumed that the last trunk of closed which may be traced from ground on release conductor 855, armature 828 and the resting contact, through the upper winding otthe switching relay 807, resting contact and armatu're' 824, wiper842, bank contact.

846,, through the winding of switching relay 861 of the line switch LS individual to the selected trunk, interrupting contacts 869 through the winding of the rotary magnet 863 to battery. Relay 807 and 861 operate i in this circuit, but due to the comparatively high resistance of relay 861 the current in the circuit is insutficient to cause the operation of magnet 863. Due to the usual mechanical interlocking arrangement between relay 861 and 862, relay 861 is permittedto operate just sufiiciently to disconnect the normal connections of ground and battery through relay 862 fromthe line conductors. Relay 807 in operating, performs the following circuit changes: Ground potentialis supplied to bank contact 846' at armature 831 and the working contact and wiper 842 to mark this trunk line busy. At armature 834, a holding circuit is closed for relay 807 which may be traced. from ground on the release conductor 855, rotary off-normal springs 839, armature 83.4 and the working contact, through the lower winding of relay 807 to battery.

Switching relay 801 energizingin its second step, efi ects the followingresults; The ground and battery connections are disconnected from'the talking conductors by the operation of armatures 811 and 815, thereby interrupting the circuit of the impulsing relay 608 in the toll transmission selector TTS. At armature 813, the ring-control conductor 857 is disconnected from the upper terminal of ring-cut-ofi relay 802 and connected to the lower terminal of this winding. 1 Relay 608, in deenergizing, closes points in the talking circuit by permitting armatures,

640 and 642 to engage their resting contacts.

By the release of armatures 641, the circuit of relay 670 and lamp L is opened and a circuit for reversingrelay 602 is closed'which may be traced tromground by way of armature 641 and the resting contact, workingcontact and armature 649, through the winding of relay 602 to battery. Relay 602 operates and performs the tollowingcircuit changes: At armature 625, ringing relay 601 1s bridged.

across condenser 695 in series with the condenser 696. A point in the initial energizing circuit of relay 608 is opened at armature 624. Ground is disconnectedfrom conductor 556 at armature 622. By the operation of armature 623 battery through the, upper winding of relay 605 is disconnected from conductor 554 and is connected through resistance 617 and the lower left-hand winding of repeating coil R to conductor 556. At armature 626 ground is removed from the ring control conductor 667, this taking place before relay 802 is deenergized, armature 813 being operated. At the same'point ground is connected to conductor 554 through the lower winding of relay 605, resting contact and armature 629, resistance 618, and the up.-

per left-hand winding of repeating coil R.

Thus, the direction oi current flow over the incoming toll trunk is reversed. Polarized. relay 502 now operates and closes the circuit oflamp L. The lighting of lamp L" indicates to the toll operator that connection has been extended to the desired line.

After being notified that the connection has been extended to the desired substation, and that the line is idle at this time, the toll operator when ready throws the key K to the ringing posit-ion, thereby connecting alter nating current across the trunk conductors. In response to this alternating current, ring;- inn" relay 601 open tes and extends ground by way of grounded. release conductor working: contact and armature 621, armature 030 and the resting contact. armature 051 and the working contact, wiper 003. .Jank contact 857, conductor 857, armature 813 and the working min-act. to the ower tcri'ninal oi iiHiE-CUt-Oll relay 80:2. Relay 802 is thereby short circuited, releases itsarmatures, and completes the ringing circuit for operating the drop signal at the P. A. X. This circuit may be traced from interrupted ringing generator cver conductor 890, lower winding of relay 802. resting contact and armature 817, armature 835 and the WOl'lZil r i .t, wiper 8&3, bank contact 8-47. conductor 882, contacts 883 of jack J through the windingof signal relay 880, contacts 884 oi jacl: J conductor 881, ha. a: contact 045. \i'i 'ior S ll. work ng contact and armature 830. to ground armature 810 and the resting contact.

lVhen the P. A. X. attendant inserts a plug in jack J to answer the call. a direct current bridge in the attendants cord circuit (not shown) is placed across the line conductors 88l.88.2, which causes the operation of rine cut-oil relay 809, in the us al way. By the operation of armatures S10 and. 817. the ringing circuit is opened and a circuit for the battery feed relay 00 of selector TTS is closed, this circuit ireludingthe upper and lower talking conductors and the line coni'luctors of the called substation in series and the right hand winding-s of repeating coil. R6. Belay 003 operates and closes a circuit for relay 004 Relay (30% operates and disconnects battery and ground connections from the conductors st and 550 at armaturcs 028 :ll tll'iQl), thereby oneuinn the circuit of pol arized relay 502 in the toll opera cord circuit CC. Polarized relay therc'l ore rcleases its armati'zrcs and inte' 'rupts the circuit of the lamp l1. The ctttinauishing of lamp L". notifies the toll operator that the called P. A. X. attendant has answered the call. Th toll-1. m n. n at tcndant ot the P. X. subscriber wanted and the attendant sets up a local connection over the P. A. X. apparatus and signals the wanted subscriber. lVhcn the subscriber answers the attendant will disconnect her telephone set "from the connection in the usual manner an the loop througrh the called sul')sci.'ib'31"s telephone set will now serve to maintain the battery feed relay of selector TTS operated.

The toll operator at the main toll board now notifies the distant toll operator that connection has been completed with the called subscriber. The distant toll operator then makes the final connection, after which the calling subscriber who initiated the toll call and the called subscriber may engage in. conversation.

At the end of the conversation both the calling subscriber and the called subscriber will replace their receivers. lVhen the subscriber at the P. A. X. substation replaces his receiver, the bridge across the line conductors S81 and S82 is opened, interrupting the circuit of the battery i'eed relay 603. Relay 003 deenergizes and opens the circuit of relay 004;. Relay :4. deenergizes and again connccts battery and ground to conductors 550 and 55% which again causes the operation of the polarized relay 504 of the toll operators cord circuit CD. ln. operatimq polarized relay 502 closes the circuit of lamp L. The l h info 0% lamp L at this time notifi s the toll operator that the subscriber at the P. A. X. substation has replaced his receiver. She thereupon ren'soves the plug P from the jack J and gives the disconnect signal to the distant toll operator by any convenient means such as by operating the key K to the signaling position, connecting alternating current acr ss the conductors of the incoming trunk (not shown).

Removing the plug P from the jack J opens the circuits of the line relay 605 in the toll transmission selector TTS by opening the bridge across the trunk conductors 501 and 502. Relay (305 deenergizes and restores its armatures to normal. The engagement of armature 681 with its resting contact places a shunt around the winding of the release relay 606, thereby causing it to deenergize, shortly after which its armatures are restored to nom nal. Relay 609 is momentarily energized during the time that armature 631 is back and relay 606 is actuated, but its operation at this time has no utility. As a result of the restoration of relay 606, ground potential is removed from release conductor at armature 683. The removal of ground potential from the release conductor 555 causes the release of the selectors TS and TTS and also oi the connector BC. The removal of ground potential "from the release cononctor also opens the circuit of the switching: relay 611 in the toll transmission selector TTS. This relay thereupon deenergizes and restores its armatures to normal. The restoration of armature 049 also opens the circuit of the reversing relay 603 which thereupon deenergizes and restores its arn'iatures to normal. A further result or" the restoration of relay 606 is the closure of the circuit for the release magnet 614 which may be traced from ground by way of the resting contact and armature 634, off-normal springs 655 closed upon the. first vertical step of the switch wipers, through thewinding of release magnet 614 to battery. Release magnet 614 energizes-and restores the switch wipers to normal in the usual manner. In connector RC a circuit'is also closed for release magnet 810 which may be traced from ground by way of the resting contact and armature 812, vertical off-normal springs 838 closed upon the first vertical step of the switch wipers, through the winding of the release magnet 810 to battery. Magnet 810 operates and causes the restoration of the wipers 841844 of the connector BC to normal. All the apparatus used in setting up the toll connection from the toll board to the P. A. X. has now been restored to normal and is ready to be used in the establishment of another con nection. The attendant releases the switches in the P.A. X. in the usual way by removing the plug from jack J I If the last trunk of the group had been busy instead of idle as just described, test relay 806 would remain operated. Relay 805, which is maintained energized during the hunting movement of the switch by reason of the fact that a circuit is closed each time armature 820 operates, being no longer energized, releases. In releasing its armature 824, a locking circuit is closed for test relay 806 from ground on release conductor 855, armature 828 and the working contact, normally closed springs controlled by armature 824, resting contact and armature 832 through the winding of test relay 806 to battery. By the release of armature-826 a circuit is closed which may be traced from ground on release conductor 855, rotary on?- normal springs 839, armature 826 and the resting contact, ofl-normal springs 837 closed on the first vertical step of the switch wipers, through the lower winding of two-step relay 801 to battery. Relay 801 operates in itssec- 0nd step, disconnecting the normal connections of groundand battery through relay 804 and magnet 809 from the upper and lower talking conductors at armatures 811 and 815, and opening theclrcuit of its initlal energizing winding at" armature 814. The dis-' connection of battery and ground from the talking conductors of the trunk causes relay 608 of tlIGtIaHSIIHSSIOD selector to release and switchover the connection to talking position as previously described and connect up the restingrcontact, armature 638 and the resting contact, lower right-hand winding of repeating coil R through the lower winding of battery feed relay 603 to battery. As a result, relay 603 energizes and deenergizes, alternately opening and closing the circuit of relay 604. Relay 604 operates its armatures 628 and 629 to intermittently open and close the circuit of the polarized relay 502 in the cord circuit CC. This causes the polarized relay 502 to intermittently open and close the circuit of the lamp L which causes the lamp to flash. The flashing of the lamp L notifies the operator that the called line is busy, whereupon she will remove the plug P from the jack J to release the connection, as previously described. Conductor 692 may be connected to an interrupter such as interrupter I shown in Fig. 1. It is preferable that a different rate of interruptions be used in the two instances so that the operator will receive different signals for line busy and all trunk busy conditions.

In the above description it was assumed that the selectors in performing their rotary hunting movement always found an idle trunk over which to extend the connection to a succeeding switch. Under extreme trathc conditions, however. there is a possibility of all the trunks accessible in a selected level of bank contacts being busy at the particular time that the testing operation is performed. In such a case the particular selector rotates its wipers past the last set of bank contacts to the eleventh rotary step in which position of course the rotary motion automatically steps, since the test wiper engages no contact;

The toll first selectors are provided with rotary cam springs which operate when the wipers are moved to the eleventh positions and connect the ground and interrupted bat terysupply to the incoming trunk conductors producing an interrupted current flow over the conductors in such a direction as to intermittently operate the polarized relay in the cord circuit and cause the flashing of the supervisory lamp. For example should selector TS (Fig. l) rotate its wipers to the eleventh rotary position, finding all trunks in the selected level busy, cam springs 511 and 512 are closed, thereby connecting ground and interrupted battery from interrupter I to trunk conductors 501 and 502, respectively. The resulting current flow through the polarized relay 502 of the cord circuit CC is such as to cause relay 502 to operate intermittently and close the circuit of lamp L The flashing of lamp L notifies the toll operatorof the all trunks busy condition encountered. I

In the toll transmission selectors a different method is employed for causing the flashing of the supervisory lamp in the-toll operators cord circuit. Should toll transmission selector TTS (Fig. 2) rotate its deencrgize.

wipers to the eleventh rotary position, finding all trunks in the selected level busy, cam springs 65? are closed, thereby connecting conductor 692 to the upper talking conductor. Conductor 692 is connected to interrupter I (Fig. 1) or a similar interrupter. A circuit for relay 603 which includes the upper righthand winding of repeating coil R is alternately closed and opened. In addition to this. the rotation ot the switch wipers (tel-(Kit oil of the bank contacts removes the ground potential from the lower terminal of the winding of switching relay 611, thereby permitting this relay to energize. Since wipers 66]. and 664; are not now connected to ground and battery through the vertical magnet of the sounding switch as they ordinarily would be it an idle trunk had been found, the circuit of holding relay 608 is opened and that relay deenergizes. Relay 608 in deenergizing closes a circuit from ground way of armature 64:1 and the resting contact, working contact and armature 649 (relay 611 now being energized) tl rough the winding of relay 602 to battery. Itelay operates and reverses the ground and battery connections to the incoming trunk conductors thereby reversing the direction of current flow through the winding of polarized relay 502 in the operators cord circuit CC which causes the relay to operate. The intermittent connection of battery to the upper talking conductor by way of cam springs causes relay (30% to energize and Rela y titlet energizes and dcenergizes correspondingly and at armature (528 and contacts controlled thereby intermittently disconnects battery from conductor These interruptions cause polarized relay 502 to energize and deenergize and lamp L flashes to indicate that an all trunks busy condition has been encountered. The operator will of course release a connection under these conditions, the release being in the manner previously described.

The utility of alarm relay 690 (Fig. 2) will now be described. lVhen toll transmission selector TTS is taken into use relay 608 operates and closes a circuit for lamp L and relay (390 from ground, armature G ll and the working contact and armature G43 and the resting contact. Lamp L lights and relay 690 operates. Relay 690 closes a circuit lamp I) and also connects ground to a signal conductor leading to the usual slow operating alarm circuit (not shown). Relay 609 operates in response to each series of digits dialed and interrupts the above circuit for relay 690 at armature 64:3. Vhen the called line is connected with or an all trunks busy condi tion is encountered, relay G08 releases and also opens the circuit of relay 690. The slow alarm circuit is adjusted so that it does not operate a signal until ground has been maintained on the alarm conductor for a longer time than is ordinarily allowed between successive digits. Should the operator tail to dial after seizing selector TTS or fail to dial the complete number, the alarm circuit will function to notify the exchange attendant oil the tac The attendant is enabled to locate the fault quickly by means of the signal lamps, lamp L being individual to a selector TTS and lamp L being common to a group oi such selectors.

Having described the invention, what is thought new and is desired to have protected by Letters Patent will be pointed out in the appended claims.

hat is claimed is:

1'. In a telephone system, operator controlled means for setting up a connection to a called line, a relay controlled by the answering of the called party for giving the operator a signal, operator controlled means for disconnecting said relay and for ringou the called line while the same in answered condition, and means for maintaining said relay operated during the ringin g operation.

2. In a toll transmission selector, a relay bridged across the talking conductors thereof, a magnet bridged across said talking conductors in series with a source of current, and means responsive to impulses for intermittently short circuiting said relay to cause said magnet to operate said switch.

3. In a telephone system, a rotary connector switch having a vertical directive movement, a rotary directive movement, and a rotary hunting movement, a trunk line terminating in said switch, a vertical magnet and a rotary magnet, means for successively bridging said magnets across the talking conductors of said trunk line, means for sending impulses corresponding to the last two digits of a called number over the two talking conductors of said trunk line in series for causing said magnets to successively operate said switch in its vertical directive and rotary directive movements, and means responsive to the completion of the rotary directive movement for disconnecting said rotary magnet from in bridge of said talking conductors and for closing a local stepping circuit for said rotary magnet to initiate the rotary hunting movement of the switch.

4. In a telephone system, two automatic switches, means for successively operating said switches to extend a connection, a double wound relay in said first switch, a stepping magnet in the second switch, means for continuously energizing said relay over a local circuit including one of its windings during the operation of the first switch, means for energizing said relay over a circuit including its other Winding and said magnet in series at the completion of the operation of the first switch, means in the second switch for opening the latter circuit at the ltll) completion of the operation of the second switch, and a second relay operated respon-' connection, stepping magnets in said selector and said connector bridge across the talking circuit in series with a'source of current,a

control relayin said selector heed up in series with one or the other of said magnets while the connection is being set up, means for cutting off the magnet at the connector to deenergize said control relay, and a battery feed bridge at said selector connected up responsive to the deenergization of said relay.

6. In a toll service trunking system, a toll transmission selector and a toll connect-or, stepping magnets in said selector and said connector, a control relay in said selector heed up in series with one or the other of said magnets while a connection is being set up, means for cutting oh the magnet at the connector to, deenergize said control relay, a trunk line extending from a switchboard to said selector, and means responsive to the deenergization of said control relay for reversing the current over said trunk line.

7. In a telephone system, two automatic switches, a trunk line extending from a switchboard to the first switch, means for successively operating said switches to extend a connection, a double wound relay in the first switch, means for continuously energizing said relay over a local circuit including one of its windings during the operation of the first switch, means for energizing said relay over its other winding over a circuit extending to the second switch at the completion of the operation of the first switch, means in the second switch for opening the latter circuit at the completion of the operation of the second switch to deenergize said relay, and means responsive to the deenergization of said relay for reversingthe direction of current flow over said trunk line.

8. In a telephone system, two automatic switches, an operators position, means for successively operating said switches to extend a connection from said position,.a double wound relay in the'first switch, means for continuously energizing said relay over a local circuit including one of its windings during the operation of the first switch, means for energizing said relay over its other winding over a circuit extending to the second switch at the completion of the operation of the first switch, means in the second switch for opening the latter circuit at the completion of the operation of the-second switch to deenergize said relay, and a signal at said position operated responsive to the deenergization of said relay.

9. In a telephone system, two automatic switches, a trunk line terminating in the first switch, a relay in the first switchbridged across the talking conductors oftsa d trunk. inev in series wi h a sou ce. of. curr nt, me n on ro led over sa d unk li e f r 311. sively operating said-switc es, t ex end a call, ontrol relay in th fi st switch en r-i gi ed'v-o e al eal-circuit du ing theope i tion of the firstswitch and over-acircuitex; tending to the second switch at 1 the temple? tion of the operation of he fir tswi ch, m ans in the second switch for opening the latter eircuitat the comp etio f th p ratio f the second switch to deenergize said control elay, a d means reepen i et he ane gization of said control relay-for reversing the conductors ofsaid trunklfine with respect os i fir tre ay n said sou c -Q eurs ntl0, InaQtelephone system, two automatic switches, a trunk line terminating in said first switch, means for establishing a normal current flow over the talking conductors of said trunk line, means for successively operating said switches to extend a call, a control relay in the first switch energized over a local circuit during the operation of the first switch and over a circuit extending to the second switch at the completion of the operation of the first switch, means in the second switch for opening the latter circuit at the completion of the operation of the second switch to deenergize said control relay, means responsive to the deenergization of said control relayfor reversing the direction of current flow over the trunk line, and means responsive to the answering of the call for Ttopping the current flow over the trunk 11. In a toll service trunking system, a toll transmission selector and a toll connector connected by a trunk line, a motor magnet in said connector bridged across the talking conductor of said trunk line, and means in said selector for controlling the operation of said magnet over the two conductors of said trunk line in series to position and conhector.

12. In a toll service trunking system, a toll transmission selector and a toll connector connected by a trunk line, a motor magnet in said connector for controlling the positioning or" the connector, a closed circuit for said magnet including a source of current and the two talking conductors of said trunk line in series, and means in said selector for altering the current flow in said circuit to control the operation of said magnet.

13. In a toll service trunking system, a toll transmission selector and a toll connector connected by a trunk line, a motor magnet in said connector for controlling the positioning of the connector, and means in said selector for sending impulses directly to said magnet over the two talking conductors of said trunk line in series.

14:. In a toll service trunking system, means for establishing a talking connection including a toll transmission selector and a toll connector, and means in said selector for repeating digits of a called number directly to the magnets of said connector over a circuit including the two talking conductors in series. 15. In a toll service trunking system, a train of serially related automatic switches including a transmission selector and a toll connector, a stepping magnet in each switch, a trunk line connecting the switches, and a line relay in the selector for operating said magnets, the magnet of the connector being operated over the two talking conductors of the trunk in series.

In witness whereof, I hereunto subscribe my name this 12th day of July, A. D. 1929.

JOHN WIGKS. 

